Related: Knowing How You Decide Is As Important As the Decision The authors, led by Uma R. Karmarkar of Harvard Business School, conducted two experiments in which they brought in volunteers and showed them a bunch of different attributes about laptop satchel bags, each displayed alongside a photo of the bag — some of them positive, some of them negative. The participants were told that all of the information they were viewing was real and that they’d eventually be tasked with actually choosing which of the satchel’s they’d most want to own.

“It is not simply the quality or the quantity of sleep that dictates mood, but rather a combination of the two,” said lead study author Patrick Finan of Johns Hopkins University School of Medicine in Baltimore.

Facing the world each morning can be difficult when you live with a mental illness. Depression, specifically, can make everyday tasks seem daunting. Getting out of bed and out the door can be a major accomplishment. And although music can’t cure depression (we wish), it’s scientifically proven to reduce stress and even depressive symptoms.

Your cortisol levels are high, and your mood is low. Because of poor sleep, your human growth hormone and testosterone production is down. You find solace in a carb-heavy, comfort-food breakfast, which sends blood sugar, and then insulin levels, soaring. This sets the stage for a sugar crash that makes you sleepy, hungry, or both.

Michael Lynn, a Cornell University professor and one of the nation’s leading experts on the psychology of tipping, has studied this at length. In one 2001 review of the literature, for example, Lynn analyzed 14 studies on more than 2,645 bills at 21 restaurants.

When your alarm blares in the morning, the snooze button can feel like your savior. Repeatedly delaying the moment when you finally roll out of bed can seriously mess with the quality of your sleep and set you up for an especially groggy day, says W. Christopher Winter, M.D., president of Charlottesville Neurology and Sleep Medicine. Think of it like this: You’ve been in deep sleep all night.

This is the first large study to look at the effects of one night of sleep deprivation on experienced physicians. The study compared outcomes for the same doctor performing the same procedure with and without sleep deprivation. “Sleep deprivation affects us all — the laboratory data is clear on that — so it did surprise me that when we looked at a broad range of physicians and evaluated the outcome of a large variety of procedures, we found no difference in the outcomes for patients whether their doctor performed overnight work the night before or did not,” says senior study author Nancy Baxter, MD, PhD, Professor of Surgery at the University of Toronto and Chief of General Surgery at St Michael’s Hospital. “So we looked at a subset of physicians who probably got very little sleep — those who performed at least two procedures overnight — and even then we didn’t find any major effect.” The findings may seem surprising given the mental effects of sleep loss. “We do know that even short-term sleep deprivation, as opposed to chronic sleep deprivation, can cause problems the following day,” says sleep expert Robert Rosenberg, DO, author of Sleep Soundly Every Night, Feel Fantastic Every Day.